The invention relates to controlling the production weight of a carding machine in direct response to the actual weight of fiber material going into a feeding system of the carding machine. Typically, a carding machine or card is fed a fiber batt from a chute feed. The chute feed has a pair of delivery rolls between which the fiber batt is delivered to a feed roll of the carding machine. The chute feed roll speed may be related to the production rate of the carding machine. The doffer roll speed (production rate) and desired weight of the web or sliver produced on the card determine the weight of the fiber batt and speed of the card feed roll. The invention relates to the control of the weight of a web which is produced from such a carding machine.
Heretofore, it has been common to sense variations in the density or weight of the fiber batt supplied from the chute feed to the carding machine and control the weight accordingly to produce a desired web weight. For example, gamma rays, displacement of one of the chute delivery rolls, a weight scale, etc. have all been used to indicate density or weight of the fiber batt. The batt weight and the speed of the card feed roll are then used to control the desired weight of the web produced by the card. U.S. Pat. No. 4,506,413 discloses one such system.
It has also been known to regulate a fiber supply machine in response to quantities of fiber stored in a fiber chute feed fed by the supply machine as in U.S. Pat. No. 4,535,511.
A weighing device is shown in U.S. Pat. No. 4,387,486 which measures the weight of a batt delivered from a chute feed to a carding machine. This signal is used to change the weight of the batt output from the chute feed so that the output weight of the web produced by the card is changed correspondingly. The speed of the card feed roll may be controlled by the weight signal to produce a corresponding desired weight output of the web from the card.
However, the problem occurs in the prior system and methods that the weight is measured while a fiber batt or web is flowing through the process which is a dynamic process. Thus, due to frictional losses and other losses, a real sensing of the weight of fiber material in the process does not occur.
It has also been known to check the weight of the web coming from the output of the card and control the speed of the card feed roll correspondingly to produce a desired web or sliver weight such as shown in U.S. Pat. No. 4,393,547. However, this involves a problem in that there is a real time lag between the sensing of the web weight and the changing of the card feed roll so that you do not get an accurate or instantaneous correction to the weight of the web by sensing on one end and correcting on the other end of the carding process.
The above methods involve sensing a function of the weight of a web or batt while it is in a dynamic flowing condition. While this may produce a representation of the fiber batt weight being fed to the carding machine or the weight of the web being produced, the prior sensing devices and methods have not sensed that actual or real weight.
It has also been known to feed a carding machine directly from an apron feeder on which fibers are deposited from a weigh pan. The output of the weigh pan may be controlled by sensing the weight of the web produced by the carding machine. However, the problems occur that there is little control over the cross sectional weight of the batt. The dumping of fibers on an apron fed directly to a card results in the card being fed in steps or lumps resulting in non-uniform weight in the lengthwise direction of the web also.
Accordingly, an object of the present invention is to control the weight of a web produced by a carding machine by sensing the real weight of fibers fed to the carding machine in a static condition.
Another object of the invention is to control the weight of a web produced by a carding machine by using the actual consumption weight of fibers delivered to the system by a weigh pan device, and a preset consumption weight.
Still another object of the invention is to provide a system and method which controls the weight of a web produced by a card in a manner that is more accurate than has been heretofore achieved by using the real weight of fibers delivered to the system as measured by a weigh pan device.
Yet another object of the present invention is to produce an accurate web weight on a carding machine by sensing actual input fiber weight and controlling the fiber supply roll, fiber delivery roll, and card feed roll in synchronization with the carding machine and one another.